Police in Thailand are no closer to finding the killers of two British tourists on an idyllic island as the distraught family of one of the victims met police in the capital Bangkok.

Four days after the bodies of Hannah Witheridge, 23, and David Miller, 24, were found with severe head wounds on a beach on Koh Tao, police investigators admitted forensic evidence had ruled out all of their suspects.

Post-mortem examinations revealed Miss Witheridge, from Great Yarmouth, Norfolk, died from head wounds while Mr Miller, from Jersey, died from severe blows to the head and drowning. A bloodstained garden hoe, believed to be the murder weapon, was found nearby.

Two British brothers who were being questioned by police have been told they are free to return home, it was reported.

And Burmese migrants on the island of Koh Tao who were arrested after blood stains were found on their clothes have also been eliminated from inquiries after no matches were found between them and DNA found on Miss Witheridge and a cigarette butt at the scene.

DNA results also indicated that semen discovered on Miss Witheridge's semi-naked body was not from Mr Miller, according to reports.

Royal Thai Police had previously insisted they had found "strong evidence" in connection with the deaths.

They have said they are now looking for three Westerners who were seen playing a guitar near the scene, on Koh Tao's main Sairee beach, the Daily Mail reported.

Speaking at a press conference on the island today, police colonel Prathum Reungthong said: "They were singing Western songs and a guitar was being played.

"We believe there were three people singing in the dark but they may have seen something or know something which could be vital.

"We are working hard at trying to find those who are in the singing group. We don't know if they are still on the island."

The family of Miss Witheridge earlier had an emotional meeting with Thailand's deputy police chief, in which they were given updates on the investigation into her death.

British consul Michael Hancock, who was also at the meeting, told reporters: "It was very important for the family of Hannah to be able to speak directly with someone leading the investigation and to hear information directly from the police.

"The family are deeply distressed at this time and my role is to support them at this very, very difficult time, and obtaining information directly and very helpfully from the police has been good for them."

Mr Hancock said the family were "very distressed" by what they had seen in the media, and appealed for privacy for them.

The bodies of the two young Britons have been moved from a forensic hospital in Bangkok and arrangements are being made by the Thai foreign ministry for them to be repatriated, the Daily Telegraph said.

Speaking at the press conference, Royal Thai Police adviser Jarumporn Suramanee said: "The reason they (Miss Witheridge's family) came to Thailand was first, to come and pick up their daughter's body, and they want to know developments in the case.

"In the event that we would like to question relatives or friends who have returned to Britain, they are willing to co-operate."

British brothers Christopher and James Ware, childhood friends of Mr Miller who had been speaking with officers but were never detained or declared to be suspects, were told they can now fly back to Jersey, Sky News said.

Thailand's military ruler apologised today for suggesting that foreign visitors to his country's world-famous beaches might be unsafe wearing bikinis.

In the face of mounting criticism, General Prayuth Chan-ocha said: "I apologise that I have spoken too harshly ... I didn't mean to criticise or look down on anyone. Today I can guarantee that Thailand is still safe ... I wanted to warn (the tourists) to be careful."

Earlier this week he claimed that foreigners visiting the south-east Asian country think "they can do whatever they want, wear bikinis wherever they like ... (but) will they be safe?"

And he was quoted as saying: "Can they be safe in bikinis ... unless they are not beautiful?"

More than 70 Thai police have been questioning migrant workers and tourists on the island, visiting hotels, bars, homes and businesses as they search for the killer.